5.9 Magnum Street Build - with dyno numbers

I can’t remember the exact clearance when I measured them. I have it in my notes, I can check later when I get home.

I bought the heads used from someone that got them from Valley Performance in Michigan and never ran them. I called the shop, and the owner was great. Told me what springs he used (Hughes 1110 and hardware), and said the guides had been reamed since they are tight from EQ. They are 2.02 valves and stainless, so assuming ordered bare and the shop built them.

When I talked to Hughes, they said I was gambling not running guides. I figured the factory didn’t so would be ok knowing the guides were fit. I do know stainless picks up on other metal easily so maybe that is why.

Engine did run on an engine stand for like 3 heat cycles and likely did 10 pulls on the dyno plus idle time. It was idling after we bumped the timing up a couple degrees for more testing when the valve stuck.

I can check the clearance notes later tonight.
It can't be "just" the stainless steel unless those particular valves are some kind of weird alloy. Plenty of factory and aftermarket cast iron heads were upgraded to stainless valves over the years and were not really prone to sticking the valves. At least not that I remember. So if clearance was adequate, either the alloy of these particular valves or the alloy of these particular heads is causing the issue. Yours caught my attention because the guides were supposed to have been sized by the shop.

Now I have no choice but to go back and install bronze liners in mine too before I run them. Been worried about that for some time and its the reason I have not used my heads yet. Same as yours; New Zealand castings.